An appropriate mechanism of a controller for avoiding the pitching up of aircrafts is for example described and illustrated in U.S. Pat. No. 3,015,458. This known control device works in dependency of both the flight Mach number and the elevator angle permissible thereby. The latter means an indirect dependency from the stationarily permissible angle of attack.
A further appropriate mechanism has become known through U.S. Pat. No. 2,953,327. This controller prevents a quasi-stationary stalling of the aircraft by limiting the load factor (n). The load factor (n), which corresponds to the permissible C.sub.L - lift value or the permissible .alpha. - value, is calculated by means of an analog circuit and is compared with the respective value from an acceleration transmitter. This arrangement amounts to an indirect determining of the permissible angle of attack by measuring the dynamic pressure and calculating the weight.
Supplementary to the known state of the art, U.S. Pat. Nos. 2,584,298, 2,923,499, 3,172,079, 3,292,882 and 3,518,621 are pointed out, in which substantially only the required underpressure at the suction side of the airfoil section or the permissible flying speed or the permissible angle of attack is used as criteria for preventing and/or indicating the upward angle of attack. These publications do not contain -- similarly to the aforementioned ones -- a disclosure of an aiming signal composed of the aerodynamic rate of change of the angle of attack, which aiming signal is required for high-speed aircrafts.
Other known, appropriate controllers stop the pitching up function too quickly primarily in dependency on the aeordynamic rate of change of the angle of attack. This method has -- as this has been proven, however, by the practice of appropriate high-speed aircrafts -- the disadvantage that the permissible maximum value of the angle of attack is only rarely exhausted or can only rarely be exhausted.
According to flight technology, it can be stated generally that the critical limit for the angle of attack at which the tendency for pitching up to occur may not be exceeded. In order to assure a pull out of the respective aircraft before it reaches this condition, an aiming signal must determine (not lastly because of the existing dynamic conditions, for example, the inertia of the aircraft) whether, and if so, how fast the aircraft approaches the dangerous condition or critical limit for the angle of attack. It therefore was obvious in existing cases and so far partly also common to feed the angle of attack and its time change as input signals into the respective controller. For this, in the practice for example through a so-called wind vane, the signal of the instantaneous angle of attack and the function of time of the rate of change of the angle of attack, which function of time is transformed by means of electric networks onto the time change of the angle of attack, are fed into the computer of the controller as a release signal. The latter means that the rate of change of the angle of attack which is taken off of the pitch rate gyro is changed through suitable filters in such a manner that after the filtering, a function of time exists which can approximately be compared with the time change of the angle of attack. A signal proportional to the angle of attack is added to same in a known mannner and the sum obtained is compared with a reference value.
These, among others, also until now built pitch up controllers, are also in certain respects considerably contridictory to the function which they are actually intended to carry out. Namely they have the disadvantage that they, due to their primary dependency on the pitch signal, also often stop the pitching up process too early and therefore in many cases cause a ground contact which actually could have been avoided.
Therefore, the invention is based on the knowledge that pitching up controllers of missiles or aircrafts cannot operate at an optimum if they are oriented exclusively on the angle of attack or exclusively on the rate of change of the angle of attack. Even if, for both controlled conditions, limits are set, these limits are not very suitably adjusted to one another and an optimum control for preventing the pitching up of missiles cannot take place with the known equipment.